Process for the stereoregular polymerization of alpha olefins

Claim 1

Process for the stereoregular polymerization of alpha-olefins of the formula CH 2 ═CHR wherein R is an alkyl radical having 1-6 carbon atoms and mixtures thereof with ethylene, which process comprises polymerizing the olefins in contact with a catalyst the starting components of which comprise (a) an addition and/or substitution reaction product of an electron-donor compound (or Lewis base) selected from the group consisting of esters of the oxygenated organic and inorganic acids with an Al-trialkyl compound or with an Al-alkyl compound containing two or more Al atoms linked together through an oxygen or a nitrogen atom, the reaction product (a) being characterized in that the amount of Al-alkyl compound present as addition compound with the electron-donor compound range from 0.01 to 1 mole per mole of the starting Al compound and in that the Al-compound present as substitution compound ranges from 0.01 to 0.9 moles per mole of the starting Al-compound; and (b) the product obtained by contacting a Ti compound selected from the group consisting of the halogenated bi-, tri-, and tetravalent Ti compounds and complexes of said Ti compounds with an electron-donor compound, with a support comprising an anhydrous bihalide of Mg or Mn and from 30% to 90% by weight of a co-support which is an anhydrous compound of an element belonging to Groups I to IV of the Mendelyeev Periodic Table and selected from the group consisting of LiCl, CaCO 3 , CaCl 2 , SrCl 2 , BaCl 2 , Na 2 SO 4 , Na 2 CO 3 , Na 2 B 4 O 7 , Ca 3 (PO 4 ) 2 , CaSO 4 , BaCO 3 , Al 2 (SO 4 ) 3 , B 2 O 3 , Al 2 O 3 , and SiO 2 , component (b) being characterized in that its X-rays powder spectrum does not show the most intense diffraction lines as they appear in the X-rays powder spectrum of normal non-activated Mg or Mn bihalides, component (b) being further characterized in that the Ti compound present therein, expressed as Ti metal, is less than 0.3 g atom per mole of the total amount of the electron-donor compound present in a combined form in the catalyst and in that the Al/Ti molar ratio is comprised between 10 and 1,000.